The present invention is directed toward a variable nut driver and more particularly toward such a device wherein the jaws of a split collet can be moved toward or away from each other by rotating a sleeve carried by the driver.
The variable nut driver described herein is an improvement over the devices shown in U.S. Pat. Nos. 3,339,439 and 3,373,639. These prior patents describe an adjustable socket wrench having a spring loaded split collet held within a tubular closure member. The jaws at the free end of the collet are normally biased away from each other. However, as a forward force is asserted on the handle, the collet closes to thereby grasp a nut or hexagonal screw head or the like.
While devices made in accordance with these two prior patents met with some success, they also suffer from a significant deficiency. These devices work well when tightening a screw since this requires forward pressure and the jaws close when a forward force is applied to the driver handle. However, when it is desired to loosen or remove a screw, forward pressure must be maintained on the screw in order to keep the jaws closed. This can make it difficult to unscrew the screw. It is also impossible to hold a screw or nut with the driver before it is applied to its proper position or after it has been removed.
Subsequent to the drivers described in U.S. Pat. Nos. 3,339,439 and 3,373,639, a tool was developed in an attempt to obviate the problems encountered with these patented devices. This improved tool, known as a Drive-All, was marketed in 1974 and 1975 by Seaboard Tools of Cherry Hill, N.J. The Drive-All also included a split collet. However, rather than requiring a forward spring force to open and close the collet, the device was provided with a sleeve member having an internal thread which surrounded a portion of the collet. The collet was provided with a pin which extended radially from the same and which engaged the thread. Rotation of the sleeve caused the pin and, therefore the collet, to move axially.
Although the Drive-All device did solve some of the problems of the previously described patented devices, it still had some problems. First, it was somewhat difficult to assemble. Secondly, because only one portion of the pin at any one time engaged the internal thread, a torquing action was being applied which frequently caused the pin to jam. Even further, because of the arrangement of the sleeve around the collet and shank portion of the driver, it was possible to turn the sleeve so far that it became disengaged from the pin thereby causing the tool to become disassembled in use.